A polybutylene terephthalate resin is used in a wide range of applications as an engineering plastic, such as automobile parts or electric/electronic parts because of having the excellent mechanical properties, electric properties, heat resistance, anti-weatherability, water resistance, chemical resistance, and solvent resistance.
For the use in automobile parts or electric/electronic parts, flame retardancy and tracking resistance are generally required. As such, various studies about improvement of flame retardancy of the polybutylene terephthalate resin composition for satisfying the UL-94 standard of Underwriters Laboratories or tracking resistance such as comparative tracking index (abbreviation: CTI) have been reported.
As specific examples of the polybutylene terephthalate resin composition having improved flame retardancy and tracking resistance, a polybutylene terephthalate resin composition containing about 30 parts by mass or more of a polyamide resin to 100 parts by mass of a polybutylene terephthalate resin, in which an organobromine compound (tetrabromo bisphenol A type epoxy resin) and a flame retardant assistant (antimony trioxide) are further added in combination, is disclosed (Patent Document 1).    Patent Document 1: Japanese Unexamined Patent Application, Publication No. H09-059497